1. Field of the Invention
The present invention relates to a self-sufficient navigation device for street vehicles, whereby the travel path traversed can be determined in terms of magnitude and direction via a path measuring device as well as an angle measuring device.
2. Description of the Prior Art
The principle of dead reckoning navigation has been known per se for quite some time, whereby, the same was primarily considered for locating systems for police vehicles and the like. In these instances, the path vector determined by dead reckoning navigation in the vehicle is reported to a central exchange, which, in turn, calculates the vehicle position therefrom and can make appropriate dispositions therewith.
Guidance system for street vehicles in individual traffic have already been proposed numerous times and, in individual cases, have already been carried out at experimental routes. Nonetheless, the employment of the same over a wide expanse has previously run into problems because such systems presume a relatively involved infrastructure. In these systems, central and decentralized fixed devices for determining and transmitting guidance recommendations to the individual vehicles are required.
Independently of such involved destination guidance systems, however, there is often only a desire for a simple orientation aid which is independent of the traffic situation. In particular, in larger cities, an automobile driver unfamiliar with the locality easily loses his orientation, even if he has undertaken a specific route at the beginning of his trip on the basis of a city map. Inasmuch as such a map provides no information concerning traffic obstacles, construction sites, turning prohibitions, usually not even concerning one-way streets, so that the driver must often deviate from his intended route and then no longer knows whether he is approaching his destination or traveling away therefrom, he is forced to stop, to inform himself concerning his new location and to select a new route on the basis of the map.
In order to provide a better possibility for orientation in such cases, it has already been proposed to control a graticule over a map or, respectively, a city plan with the assistance of a dead reckoning system in such a manner that one's own location is always identified. This not only requires maps to scale which are specifically suitable for the vehicle device, but, rather, also requires a device which can be readjusted to different scales, since maps having different scales must be selected at least between orientation in a metropolitan area and orientation in cross-country journeys. The decisive disadvantage of this known device, however, is that the automobile driver receives a display of only his location, but not of his destination so that he is forced again and again to stop, to seek his destination on the map and to select his direction of travel from the location displayed.